I post a lot about how the Catholic Church and the Mormons are against gay marriage, but I rarely post about other highly influential religious groups that are very anti-gay marriage, and this is one big reason why gay marriage lost in Illinois recently. The article I'm linking to below is from Huff Po and it's one of the few I've seen go into detail about this topic.
The ministers of many of the African-American churches in Illinois turned this issue into a crusade. As the Chicago Sun-Times reported, the members of the House faced "a withering lobbying blitz against" the legislation from black ministers. The message of the ministers was direct: "Vote against us on this issue and we will defeat you in the next election." Faced with such pressure, members of the House Black Caucus caved, at least for the moment.
The article gets into more statistics and examples. You can read the rest here. As usual, the comment thread is also fascinating.
The only comment I have is that I know many people in the LGBT community who are of African American descent. Before I met Tony, I dated a guy of African American descent for over a year and although we were too busy having fun at the time to get political, I do remember how difficult it was for him to be openly gay unless he was in a safe place where no one knew him. It's one of the main reasons we broke up. Last I heard he married a woman. I don't know what happened after that.
I don't think this is a racial issue, not by any means. I think some would like us to believe that, but it doesn't work for me because I know better. It's a religious issue and there are many churches fighting against equality and gay marriage. But the reality so many religious zealots fail to see is that we live in a country that's supposed to believe in the separation of church and state.